Case studies considered as retroactive experiments

A methodology for combining automobile crash investigation case studies into an overall statistical analysis is presented. The method considers each case study as an experiment identified by a set of independent variables. For each experiment a dependent variable—such as occupant injury—is measured. Analysis of the relationship between the independent variables and the dependent variable can then he performed. A specific example which uses multiple regression analysis to fit an injury prediction model is presented. Residuals from this model are used to show the effect on injury reduction of restraint systems.